Ag Weather Forum

Favorable weather conditions during most of June and July across Western Canada allowed crops to catch up after a late spring planting season plagued by low temperatures and late-season snow. While all seems well, we are now seeing some potential snags in what has been a pretty good summer growing season.

The upper level blocking pattern that brought some of the heavy snow and low temperatures from late in the winter and well into the spring has begun to reappear across North America. Despite being the time of year when subtropical ridges normally will dominate, we are seeing weather patterns begin to shift across Canada to match those typically seen during the early or middle of fall.

While we are not calling for snow and severe cold anytime soon, we do feel that the developing pattern of a blocking high pressure area across the northern half of Western Canada and the resulting downstream eastern Canadian trough may bring enough cool weather during the next week or 10 days to slow crop growth during the important crop advancement season.

The evolving weather pattern will allow for high pressure to grow across western and north-central Canada allowing cool weather to expand and shift southward across a large portion of Central Canada. Some of this cool weather will expand west into the Prairies. The greatest threat for cool weather will be across the eastern and southeastern Prairies with the west expected to stay a little milder.

This pattern initially should be generally dry, but further down the road, maybe by later next week, the jet stream flow may begin to bring some moisture in from the Pacific Northwest of the U.S. and could result in some increase in rain across western and southern regions.

Soil moisture conditions are currently mostly favorable for much of the crop region and with lower-than-normal temperatures expected during the coming week or more we would not expect a major dissipation of this moisture. If rains increase as we move further into August, that could become another negative factor for some areas.

The low temperatures' potential impact comes in the form of slowing crop development. While not a big problem at the current time, the cool readings could result in crops not maturing in time to evade any early season frost or freeze conditions later in August or September.

Blocking patterns such as the one that is now evolving are difficult to forecast, since they tend to come along without much warning. These patterns also can linger longer than expected and the computer models we use are less than perfect in forecasting the intensity and extent of blocking high pressure. Summer is not a normal time for high latitude blocking patterns which likely adds more uncertainty to the forecast during the next few weeks.

Doug Webster can be reached at doug.webster@telventdtn.com

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